Read Bill Jordan, Cuningham, Ed McGivern. Jordan stated that it was necessary for riding in a car and that the forward tilt did not slow down a fast draw. That is why I am asking, "...Is there supposedly some drawing or other advantage for the tilt, other than comfort while seated?..."
So far from the posts, it would seem that if a person's body had a slight inward curve above the hip, the canted gun would fit into it better for both comfort and concealment.
Anything else?